Molded shear slip

ABSTRACT

A molded slip assembly comprises a shear ring coupled to a plurality of slip segments to form a unitary solid ring and a plurality of drillable bases. A drillable base is molded to an inner surface of each of the plurality of slip segments.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser. No. 62/038,141 filed on Aug. 15, 2014, and entitled “Molded Shear Slip,” which is hereby incorporated herein by reference for all purposes.

BACKGROUND

This disclosure relates generally to methods and apparatus for anchoring downhole tools in a wellbore. More specifically, this disclosure relates to methods and apparatus for anchoring downhole tools in a wellbore using a slip assembly at least partially constructed from drillable materials.

In drilling or maintain wellbores, it is often desirable to anchor a downhole tool within the wellbore. Downhole tools that are often anchored in wellbores include, but are not limited to, packers, bridge plugs and frac plugs, and are well known in the art of producing oil and gas. These types of downhole tools are generally used to isolate the portion of the wellbore below the downhole tool from the portion of the wellbore above the tool. Thus, these types of downhole tools are often subject to high differential pressures.

Many downhole tools utilize toothed, wedge-shaped components, known as slips, to anchor the tool in the wellbore with sufficient force to resist the differential pressure and maintain the position of the tool within the wellbore. These slip elements are commonly used in setting or anchoring of tubing hangers, packers, bridge plugs, and frac plugs. In addition to holding the downhole tool in place in the wellbore, the slips are often used to lock components of the tool into place so that sealing elements can remain energized.

In many downhole tools, the slips are initially retained in close proximity to a mandrel and then forced outwardly away from the mandrel as the slips are moved axially relative to a cone-shaped member. In order to engage the wellbore, whether cased or open hole, slips generally have external features, such as teeth, buttons, wickers, or other protrusions, that bite into the inner wall of the wellbore.

In certain applications, once selected operations are complete it is desirable to remove the downhole tool from the wellbore. To facilitate this removal, downhole tools, or portions thereof, can be constructed from drillable materials, such as plastics, composites, cast iron, and other materials that provide sufficient strength but can be more easily drilled that conventional alloy steel.

Because slips must have sufficient strength to anchor the downhole tool in the wellbore, constructing slips from easily drillable materials can be challenging. Thus, there is a continuing need in the art for methods and apparatus for providing anchoring of downhole tool with drillable slips.

BRIEF SUMMARY OF THE DISCLOSURE

A molded slip assembly comprises a shear ring coupled to a plurality of slip segments to form a unitary solid ring and a plurality of drillable bases. A drillable base is molded to an inner surface of each of the plurality of slip segments.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more detailed description of the embodiments of the present disclosure, reference will now be made to the accompanying drawings, wherein:

FIG. 1 is an isometric view of a molded shear slip assembly.

FIG. 2 is a partial sectional view of a molded shear slip assembly installed on a downhole tool.

FIG. 3 is a partial isometric view of a molded shear slip assembly installed on a downhole tool.

DETAILED DESCRIPTION

It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.

Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein.

Referring initially to FIG. 1, a molded shear slip assembly 10 comprises a unitary solid ring 12 molded to a drillable base 14. The unitary solid ring 12 comprises a profiled outer surface 16, a profiled inner surface 18, and a shear ring 20. In certain embodiments, the outer surface 16 may be profiled to include a plurality of angular teeth 17 arranged so as to bite into the surrounding wellbore and prevent movement in one direction relative to the slip assembly 10. The inner surface 18 may be profiled to include a plurality of radial ridges 19 or other features that assist in coupling the unitary solid ring 12 to the drillable base 14. A plurality of axial slots 24 is formed in the unitary solid ring 12 so as to form a plurality of slip segments 22.

The unitary solid ring 12 may be constructed from a single cylindrical piece of material. The profiles can be machined into the outer surface 16 and inner surface 18 and then the plurality of slots 24 cut. When the plurality of slots 24 is cut, the slot is machined so as to leave a portion of the material in place to form the shear ring 20. In other embodiments, the slip segments 22 can be constructed as separate pieces and then assembled onto a shear ring 20 to form the unitary solid ring 12. The unitary solid ring 12 may be constructed from any material suitable for engaging a wellbore, including, but not limited to, alloy steel, cast iron, other metal alloys, and composite materials.

Once the unitary solid ring 12 is constructed, it can be placed in a mold and the drillable base 14 molded to each of the slip segments 22. The drillable base 14 may be formed from a drillable material, including, but not limited to, thermoset plastics, polymers, resins, and composite materials. In certain embodiments, the drillable base 14 is molded to the slip segments 22 so that, once released from the mold, the shear slip assembly 10 is ready for use without further processing.

Referring now to FIGS. 2 and 3, the shear slip assembly 10 is shown assembled onto a downhole tool 36. The shear slip assembly 10 is disposed about the mandrel 20 and axially constrained between a spacer ring 32 and a setting cone 34. The downhole tool 36 is set by moving the setting cone 34 axially toward the spacer ring 32. As the setting cone 34 moves axially toward the spacer ring 32, the shear slip assembly 10 is axially constrained by the spacer ring 32 and the setting cone 34 will move under and apply a radial outward force to the shear slip assembly 10. The radial outward force will continue to increase until the shear ring 20 fractures and allows the slip segments 22 to move outward and engage the surrounding wellbore.

The shear ring 20 is sized so that the slip segments 22 will stay interconnected until a desired setting force is reached. This helps to ensure that the sealing elements, or other components, of the downhole tool 36 are fully energized before the slip segments 22 lock the downhole tool 36 in place in a wellbore. The shear ring 20 may have a generally uniform cross-section or may include one or more weakened portions arranged to facilitate fracturing of the shear ring 20. The weakened portions may include notches, grooves, or other reduced cross-sectional area portions.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and description. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the disclosure to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present disclosure. 

What is claimed is:
 1. A molded slip assembly comprising: a plurality of slip segments; a shear ring coupled to the plurality of slip segments to form a unitary solid ring; and a plurality of drillable bases, wherein of the plurality of drillable bases is molded to an inner surface of each of the plurality of slip segments.
 2. The molded slip assembly of claim 1, wherein the unitary solid ring is formed from a single piece of material.
 3. The molded slip assembly of claim 1, wherein the unitary solid ring is formed by coupling the plurality of slip segments to the shear ring.
 4. The molded slip assembly of claim 1, wherein the plurality of drillable bases is molded to the plurality of slip segments at the same time.
 5. The molded slip assembly of claim 1, wherein the unitary solid ring is a composite material.
 6. The molded slip assembly of claim 1, wherein the plurality of drillable bases includes a composite material.
 7. The molded slip assembly of claim 1, wherein the plurality of drillable bases includes a thermoset plastic.
 8. A downhole tool comprising: a mandrel; a setting cone moveably coupled to the mandrel; and a molded slip assembly disposed about the mandrel, wherein the molded slip assembly includes a unitary solid ring having a plurality of slip segments coupled to a shear ring and a plurality of drillable bases, wherein one of the plurality of drillable bases is molded to an inner surface of each of the plurality of slip segments, wherein the plurality of drillable bases is in contact with the setting cone.
 9. The downhole tool of claim 8, wherein the unitary solid ring is formed from a single piece of material.
 10. The downhole tool of claim 8, wherein the unitary solid ring is formed by coupling the plurality of slip segments to the shear ring.
 11. The downhole tool of claim 8, wherein the plurality of drillable bases is molded to the plurality of slip segments at the same time.
 12. The downhole tool of claim 8, wherein the unitary solid ring is a composite material.
 13. The downhole tool of claim 8, wherein the plurality of drillable bases includes a composite material.
 14. The downhole tool of claim 8, wherein the plurality of drillable bases includes a thermoset plastic.
 15. A method comprising: forming a unitary solid ring having plurality of slip segments coupled to a shear ring; molding a drillable base onto each of the plurality of slip segments.
 16. The method of claim 15, wherein the unitary ring is formed by a method comprising: forming an outer profile on an outer surface of a cylinder; and forming a plurality of axial slots in the cylinder to form the plurality of slip segments, wherein the plurality of axial slots is formed so that the shear ring is coupled to the plurality of slip segments.
 17. The method of claim 15, wherein the unitary solid ring is formed by coupling the plurality of slip segments to the shear ring.
 18. The method of claim 15, wherein the drillable base is molded to each of the plurality of slip segments at the same time.
 19. The method of claim 15, wherein the drillable base includes a composite material.
 20. The method of claim 15, wherein the drillable base includes a thermoset plastic. 